Control for dual engine vehicles



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CONTROL FOR DUAL ENGINE VEHICLES Filed June 13, 1956 5 Sheets-Sheet 4MNl/HL CONTROI- VIYCUUM VLVE 77 BOOSTER VFNT ENGINE DmvEN 7 PRIMHRY ENlNE vflauuM PUMP HccELERHToR P5061. 73

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NMF To vgwun CYLINDER April 3, 1962 J. WOLF CONTROL FOR DUAL ENGINEVEHICLES 5 Sheets-Sheet 5 Filed June l5, 1956 CLUTLH BOOSTER 6 ONVERTETIYHNSMISSIUN 5 uva/Muna Tanga/l) 6 n, w w 5 Z m ./Z 7 ,1. m 5 m 7j J ff j f 00 fj Z 0 d. y /J a M z n /1 m// wa y Unite States atent Cdl-ice3,027,962 Patented Apr. 3, 1962` 3,027,962 CONTROL FOR DUAL ENGINEVEHICLES Lloyd J. Wolf, 99 Woodland Road, Irving, Tex; Filed June 13,1956, Ser. No. 591,183 7 Claims. (ci. 18o- 77) My invention relates tomotor vehicles and is concerned primarily with providing an additionalengine whose control is related to the speed of its propellingconnection without any necessity for synchronizing both enemies Theinvention is applicable to motor vehicles generally and will bedescribed in one instance as applied to a tractor-trailer vehicle inwhich the additional engine is mounted on the trailer, and in otherinstances by'showings of the same COILGCpt in relation to a motorvehicle of the nonftrailer type, such as ordinary trucks and buses whichare normally equipped with single engines.

In the usual vehicle of the tractor-trailer type, tthe entire powerplant is mounted on the tractor and, since the engine and transmissionmust be sized to move the dead load of the tractor and trailer plus thepay load on the trailer, the tractor must be designed accordingly totransmit the whole tractive effort to the vehicle. This arrangementrequires a heavy construction in the tractor with a correspondingreduction in the amount of Ythe pay load on the trailer. y

Moreover, with such a vehicle, diiculty is experienced in climbing steepgrades and it is necessary toprovide the tractor transmission with a.relatively large number of speed ratios to negotiate varying roadconditions as well as those encountered in lcross-country movements,such as in pipe laying operations. At best, this arrange'- ment providesfor crawling movements in hilly Vcountry land owing to the absence ofany tractive 'eifortl `'by the trailer wheels, movements acrossunimproved Vground frequently necessitates the use of an additionaltractor. Single engined buses and trucks are also characterized by thesame operating difliculties. y Y i A Attempts to solve this problem haveusually consisted in mounting an additional engine on the trailer, or onthe bus or truck, and conditioning both-engines for synchronizationthrough connection to common accelerator and clutch pedals, by arrangingboth transmissions to run at the same speed, or a combination of thesefalctors. In the first arrangement, each time that a gear shift is madein the tractor and trailer transmissions,l the accompanying movements ofthe accelerator and clutch pedals interrupts power iiow from the tractorand trailer engines simultaneously. The vehicle therefore loses headwayand if then climbing ahill, the power interruption occurs at a time whensustained power ow is most needed. Substantially the same result occurswhere the tractor and trailer transmissions are arranged forsynchronization since both of theseunits would be shifted together withconsequent interruption of power ilow from both engines. y

The traverse of steep grades and poor acceleration also present seriousproblems in .the operation of single engine trucks and buses,particularly where it is important to meet tight schedule requirements.

It is therefor the principal object of my invention to provide a motorvehicle having a main or primary engine and an additional or boosterengine whosethrottle system is vacuum operated and responsive to thespeed of its propelling connection.

A further object is to provide `a tractor-trailer vehicle in which powerdistribution is .effected by mounting an engine on the tractor and anindependently controlled engine on the trailer which isavailable asrequired.

This application is a continuation-impart of `my `copendingappplication, Ser. No. 187,769, filed September 30, 1950, which hassince become abandoned.

These and further objects of the invention will be set forth in thefollowing specilication, reference being had to the accompanyingdrawings, and the novel means by which the objects are etectuated willbe definitely pointed out in the claims.

In the drawings:

FIG. 1 is -a side elevation of a tractor-trailer vehicle embodying theinvention in which the trailer includes a multispeed, rear axle.

FIG. 2 is a schematic view showing the relation of the trailer enginethrottle, transmission and rear axle speed controls for the vehicleshown in FIG. 1.

FIG. 3 is an enlarged, fragmentary and diagrammatic view yshowin-g therelation of the Vacuum control elements for determining the position ofthe trailer engine throttle valve as viewed in FIG. 2, the vacuumcontrol valves being shown in positions corresponding to the idlingPOsition ofthe throttle Valve.

FIGS. 4 and 5 are sectional views of the transmission control vacuumvalve in FIG. 3 in positions determined by the low and driving rangesofthe transmission, respectively, andv in each of which positions, themanual control vacuum lyalve may be rocked to provide any desiredopening of the trailer engine throttle Valve beyond idling. 4

FIG. 6 is an enlarged, fragmentary and sectional elevation of themanual. control vacuum valve in FIG. 3 in approximately iirst automaticposition, i.e., a position such'that the vacuum system rst beginsautomatic functioning to effect opening of the throttle valve beyondidling position.

FIG. 7 is 'an enlarged, sectional view of the axle gear selector valvetaken along a plane parallel to that in which the valve is shown in FIG.2.

FIG. 8 is a diagrammatic view, partly in section of a modilied vacuum'control on the additional or booster engine which is linked with thethrottle control on the primary engine.

FIG. 9 is -a sectional view of a valve which is connected to theaccelerator pedal lfor the primary engine and forms a part of the vacuumcontrol for the throttle of the booster engine and which will providefull throttle on the booster engine whenever the primary engine throttleismoved to full open position.

FIG. 10 is a schematic view, partly in section, sho- Wing an additionalcontrol for use in connection with the FIG. 9 valve when used with atractor-trailer vehicle.

FIGS. lland 12 are schematic views of a side-by-side engine equippedvehicle and of a tractor-trailer vehicle when provided with the FIG. 8control, the numerical designations generally of the tractor, trailerand their transmissions and propelling connections being the same as inFIG. 1 with the exception of the trailer rear axle.

The trailer transmission includes a hydraulic coupling or a hydraulictorque converter and devices of this type which are suitable are thosemarketed under the trade marks Dynaflo and Hydramatic in which the gearsare in constant mesh and change of speed ratios from low to high isfully auomatic. Also suitable is the well known .four speed transmissionwhich the gears are always in mesh, but which is not fully automaticthrough the four speeds. An automatic shift from first to second speed,constituting one range, is effected by a vacuum system which `becomesoperative when the driver lifts his foot from the accelerator pedal, buta shift from second to third speed is manually controlled.A Thistransmission has a neutral position. A fourth alternative is amodification of the last noted transmission wherein the gear.arrangement is of the clash gear type 3 but controlled as indicated toprovide low and driving ranges.

Referring to the drawings, FIGS. 1 to 7, inclusive illustrate atractor-trailer vehicle which is characterized byy automatic throttlecontrol of the trailer engine, a speed controlled selection of the lowand driving ranges of the transmission, and a multispeed ratio in thetrailer rear axle.

Referring to FIG. l, the numeral `1t) designates the modified vehiclecomprising a tractor 11 and a trailer 12. The tractor includes the usualengine 13 and transmission 14 which are controlled in the customarymanner and connected through a propeller shaft '15 to the tractor rearaxle 16.

The forward end of the trailer 12 is coupled to the rear end of thetractor in the usual manner and the former may be of any conventionaltype except for the power plant, transmission, rear axle and thecontrols therefor as presently described. Suitably carried on the underside of the trailer 12 is an internal combustion engine 17 which isconnected to an automatic transmission 18 having a low and a drivingrange, such as present commercial forms of the Dynaiio and Hydramatictransmissions. For purpose of illustration, it will be assumed that thetrailer is equipped with a Dynaflo transmission and that the trailerengine is of the gasoline type. The output end of the transmission 18connects through a propeller shaft 19 to the trailer driving rear axle20 which will be regarded as of the two speed type and will be here.

inafter described. The controls for the parts noted above areschematically illustrated in FIG. 2 to which reference will now be made.

In this figure, all parts to the left of the line A-A are carried by thetractor 11 and those to the right by the trailer 12. A battery 21 hasone terminal 21a grounded while the other terminal 2lb connects by awire 22 with wires 23 and 24 which in turn respectively connect with oneside of so-called rnicroswitches 25 and 26 of usual construction. Thebattery is generally any source of electrical power and its voltage ismaintained in the conventional way by a generator (not shown) which isdriven by the tractor engine 13. The other side of the switch 25connects by a wire 27 which one side of the coil of a low range solenoid28 and the opposite end of this coil connects by a wire 29 with oneterminal of a transmission switch 30 whose other terminal connectsthrough a wire 31 and main switch 32 with ground.

The other side of the microswitch 26 connects by a wire 33 with one endof the coil of a driving range solenoid 34 whose opposite end connectsby a wire 35 with the wire 29 and hence with the switch 30.

The microswitches 25 and 26 include the usual plungers 36 and 37,respectively, whose movement inward of the switches closes the same andthis closure is maintained for a predetermined time when the plungersmove outwardly, the plungers being biased outwardly towards openpositions by parts of the switch structure. Switches of this type aregenerally characterized by a snap action and the plungers by shortmovements'and are well known in the art, a typical arrangement beingshown in U.S. Letters Patent No. 1,960,020, dated May 22, 1934. Theplungers 36 and 37 cooperate respectively with screws 38 and 39 mountedon a rock arm 40 forming part of a typical speed responsive governor 41,only shown diagrammatically in FIG. 2. The internal construction of thegovernor is such that, as the speed of the governor shaft 42 increases,the arm 40 rocks clockwise and, upon a decrease in speed, the arm =40moves towards the position shown in FIG. 2. The governor shaft 42 isdriven from the tractor propeller shaft 15 by means of a belt-pulleyconnection designated generally by the numeral 43.

The solenoids 28 and 34 are utilized to condition the transmission 18for its forward, low and driving ranges, respectively, and the means foraccomplishing this result 4 will now be described. The core 44 of thesolenoid 28 is connected by a link 45 with the free end of atransmission gear selector arm 46 which is carried by the transmission18 and connected internally thereof in the well known manner todetermine neutral and forward drive through the transmission. The core47 of the solenoid 34 is also connected to the arm 46 through a link 48radially inward of the connection of the link 45 thereto, but one end ofthe link 48 carries a pin 49 which operates in an elongated slot 50 inthe arm 46 for a purpose presently explained and the stroke of the core47 is less than that of the core 44. The arm 46 is biased to the neutralposi- 4 tion indicated by the numeral 52 in FIG. 2 by a spring 511 whoseopposite ends are respectively connected to the arm and a convenientpart of the transmission 18.

From the above, it will be apparent that when the switches 30 and 32 areclosed and the rock arm 40 is either in the position shown in FIG. 2 orin a slightly rocked position, as determined by the speed of thepropeller shaft 15, the solenoids 28 and 34 are energized to therebyrock the arm 46 to the low range position of the transmission 18,indicated by the numeral 53 in FIG. 2, the solenoid 28 performing theprimary duty in this connection by reason of the longer stroke of itscore 44 and the pin-slot or lost motion connection of the core 47 to thearm 46 enabling the latter to override the pin 49.

'Ihe screws 38 and 39 are adjusted in relation to the strokes of theplungers 36 and 37, respectively, and the movement of the arm 40 so thatas the speed of the propeller shaft 15 increases yand the arm.- 40 rocksin a clockwise direction, the screw 38l iirst breaks engagement with theplunger 36 which thereby moves to an open Aposition and interrupts thecircuit through the solenoid 28. The energization of the solenoid 34 ismaintained by engagement of the screw 39 with the plunger 37 whichcontinues to close its circuit so that the return of the transmissiongear selector arm 46 under the pull of the spring 51 is limited to thedriving range position indicated by the numeral 54 in FIG. 2. When thespeed of the propeller shaft 15 has reached the top regulating speed asdetermined by the settings of the governor 41 and screw 39, the furthermovement of the arm 40 separates the plunger 37 and screw 39, thusopening the switch 26, deenergizing the solenoid 34 and permitting thearm 46 to return to neutral position 52 when power flow through thetransmission ceases. When the speed of the propeller shaft 15 dropsbelow the top regulating speed, the screw 39 first engages the plunger37 to condition the transmission 18 for its driving range through thesolenoid 34 and if the propeller shaft speed drops further to asufficient extent, the screw 38 engages the plunger 36 and conditionsthe transmission 18 for its low range through the solenoid 28.

Advantage is taken of the propeller shaft speed ref sponsive movementsof the arm 46 to provide an automatic positioning of the trailer enginethrottle Valve through a vacuum system which will -now be described (seeFIGS. 1 to 6, inclusive).

The opposite ends of a link 55 are respectively connected to the arm 46and to one end of an arm 56 whose opposite end connects with a rotor 57(see FIGS. 3 and 4) forming part of a transmission control vacuum valve58 that includes a casing 59 and a cylindrical chamber 60 within whichthe rotor 57 rocks. The rotor 57 includes a parti-diametral pocket 61which is open at one end and against the base thereof seats a spring 62which biases a ball 63 into contact with the -annular wall of thechamber 60. Recessed in the annular face of the rotor 57 is aparti-annular channel 64 whose length will be presently established. Thechamber 60 includes a plurality of ports circumferentially spacedtherearound, specifically ports 65, 66, 67 and 68. The port 65communicates through an exhaust passa-ge 69 in the casing 59 with theatmosphere, while the ports 66, 67 and 68 communicate,

respectively, with the ends of hoses 70, 71 and 72, also mounted in thecasing 59.

The other end of hose 7) connects with a vacuum pump 73 of conventionaltype suitably driven by the trailer engine 17, so that its capacityvaries with the speed of this engine. The other end of hose 71 connectswith the outer end of a passage 74 (see FIG. 3) that extends through thewall of a casing 75 forming part of a manual control vacuum valve 76located in the tractor cab, the inner end of the passage 74 terminatingin a port 77. The casing 75 also includes -a vent passage 78 extendingthrough the wall thereof and spaced clockwise from the passage 74.Rockable within the casing 75 is a cylindrical rotor 79 which isactuated by an external handle 80 and which includes in the annularsurface thereof a parti-annular channel 81 that, in the off position ofthe handle shown in FIG. 3, provides communication between the vent 78and the passage 74 and thus with the hose 71. The other end of the hose72 communicates with one end of a vacuum cylinder 82 in which isreciprocable -a piston 83 that is biased against an internal shoulder 84at the opposite end of the cylinder by -a spring 85. On the other sideof the piston 83 from the spring 85 is a chamber 86 which communicateswith the atmosphere through a port 87. The piston 83 is attached to oneend of a rod forming part of a linkage, generally indicated by thenumeral 88, whose opposite end connects with an arm 89 (see FIG. 1) thatis attached to a throttle valve 90 in the carburetor 91 of the trailerengine. Movements of the linkage 88 towards the left, as viewed in FIG.3, shift the throttle valve 94) in an opening direction, this valvebeing shown in idling position in FIG. 1.

Referring to FIG. 3, it will be noted that, with the parts in thepositions shown, i.e., with the engine 13 idling and the arm 56 shiftedto the idle position by the arm 46 so that the trailer engine is nottransmitting power to the axle 26, the position of the valve rotor '7 issuch that the ball 63 masks the port 66, thus disconnecting the vacuumpump 73 from the valve 58, and that the portion of the cylinder 82 tothe left of the piston 83 is at atmospheric pressure by reason of thefact that the hose 72 communicates through the port 68, channel 64, port65 and passage 69 with the atmosphere. In other words, the length of thechannel 64 is such that, with the rotor 57 in the position shown in FIG.3, it connects the ports 65, 68 and 67, but ends short of the port 66.The spring 85 therefore holds the piston 83 in the position shown whichcorresponds to the. idling position of the throttle valve 9i). Also withthe handle 80 in the position shown, atmospheric pressure exists in thehose 71 since the interior of the latter communicates with theatmosphere through the passage 74, port 77 which is fully open, channel81 and vent 78.

In describing the operation of the vehicle shown in FIG. l so far asdescribed, it -will first be assumed that the vehicle is at rest withthe tractor and trailer engines 13 and 17 idling, respectively, andhence the vacuum pump 73 operating, each of these engines having beenstarted in the conventional manner. At this time, the switches 30 and 32are open (see FIG. 2), the governor arm 40 is in the retracted positionshown so that the microswitches 25 and 26 are closed, and since thesolenoids 28 and 34 are deenergized by reason of the open switches 30and 32, the gear selector arm 46 is in the neutral position shown.Further, the several parts of the vacuum system occupy the relativepositions shown in FIG. 3 in which the vacuum pump 73 is cut off fromthe cylinder 82 by the ball 63.

The driver starts the vehicle moving by connecting the tractor engine 13to the propeller shaft 15 through the usual clutch (not shown) and thetransmission 14 in the conventional manner and either before, after, orsimultaneous therewith, he closes the switches 30 and 32 to therebyenergize the solenoids 28 and 34 and rock the gear selector arm 46 tothe low range position 53 (see FIG. 2). At the same time, the connectedarm 56 moves to the position shown in FIG. 4 in which the rotor 57 masksthe exhaust port 65 and the ball 63 uncovers the port 66. The vacuumpump 73 then connects through the channel 64 with the hoses 72 and 71and therefore respectively with the cylinder 82 and the manual valve 76.However, with the latter in the position shown in FIG. 3, i.e., with thehose 71 connected through the fully open port 77 to the atmospherethrough the vent 78, the pump 73 is incapable of establishing suflicientvacuum to the left of or behind the piston 83 so that atmosphericpressure acting through the port 87 can move the piston 83 and hence thelinkage 88 in a direction to further open the throttle valve 90.

Preferably, the manual valve rotor 79 is rocked clockwise to theapproximate position shown in FIG. 6 before, after or simultaneouslywith the closing of the switches 30 and 32. The rotor 79 then partiallymasks the port 77 and reduces the air flow through the hose 71 to anextent that enables suflicient vacuum to be established behind thepiston to shift the throttle valve 90 to what is known in the art as afast idle position and which will be regarded for present purposes asthe first automatic position. This term will be subsequently explained.The rotor 79 can be held in this position in any approved manner, whichdoes not interfere with a further clockwise movement of the rotor. Thefirst automatic position of the rotor 79 shown in FIG. 6 is diagrammaticonly as it will be apparent that the actual position will depend uponthe sizing of the related ports and passages and the capacity of thepump at the trailer engine speed in question.

It will be obvious that, with the trailer engine idling fast, a furtherclockwise movement of the rotor 79 effects a further throttling of airow through the hose 71, a higher vacuum in the cylinder 82 and hence afurther opening of the throttle Valve 94) which increases the speed ofthe engine. When the rotor 79 completely masks the port 77, the throttlevalve 9) is fully open. The handle 8i) can be located in any positionbetween fast idle and full open positions of the throttle valve 9i)depending upon the power required of the trailer engine and left there,even when the trailer engine cuts out for reasons presently explained.

As the vehicle increases in speed, the governor arm 40 moves clockwiseand at a speed `determined by the adjustment of the screw 38, themicroswitch 25 opens while the screw 39 maintains closure of themicroswitch 26. Accordingly, the solenoid 28 is deenergized and thespring 51 returns the gear selector arm 46 to the driving range position54 shown in FIG. 2 as determined -by the pin 49 which is held in thisposition by the still energized solenoid 34.

Accompanying the shift of the arm 46 to position 54 is a rocking of thearm 56 to the position shown in FIG. 5 and while the rotor 57 rotatesclockwise, it still will mask the exhaust port 65 and leaves the ports66, 67 and 63 in communication with each other and with the vacuum pump73. Hence, positions of the throttle valve 90 can be regulated by thevalve 76 in the manner described above to provide any desired speedratio between the tractor and trailer engines, each of which assumes itsshare of the total load without either engine pushing the other.

If with the arm 46 in the driving range position, the speed of thevehicle drops sufficiently to cause the governor arm 40 to rockcounterclockwise and close the microswitch 25, such as when climbing ahill, the arm 46 is shifted to the low range position 53, thus takingadvantage of the easier speed ratio in the transmission v18. Whether ornot the shift to the low range position will require a differentposition of the throttle valve 90 will depend upon the judgment of thedriver in relation to the road conditions and the total power available.It may be advantageous, particularly if the vehicle speed continues tofall, to select a different gear ratio in the tractor transmission 14.During this gear shift, power iiow from the tractor engine 13 to thetractor rear axle 16 is interrupted and an important feature of theinvention is that, during this shift, power flow to the trailer rearaxle is maintained so that very little change inthe headway of thevehicle occurs.

As already noted, the goveronr 41 and screw 39 are adjusted so that atsome predetermined or top regulating speed of the propeller shaft 15,the governor arm 46 rocks clockwise sufficiently to open the microswitch25 and deenergize the solenoid 34, the microswitch 25 being already openat that instant as described above. This action will occur with the gearselector arm 46 in driving range position 54 which is accordinglyshifted to neutral position 52 by the spring 51 so that the trailerengine 17 is disconnected from the trailer propeller shaft 19. If thespeed of the propeller shaft 15 falls below the top regulating speed,the arm 46 is restored to driving range position 54 and power flow fromthe trailer engine is resumed.

A further important advantage is that when the transmission 18 shiftsfrom driving range to neutral at the top regulating speed of thepropeller shaft 15, it is unnecessary to change the position of thehandle S for the purpose of moving the throttle 90 to fast or ordinaryidling position. The handle 80 is left in whatever position it occupiedwhen power ilow from the trailer engine was interrupted and the shiftingof the arm 56 by the arm 46 to the position shown in FIG. 3 causes theball 63 to close the port 66 and hence interrupt the influence of thevacuum pump 73 while, at the same time, the exhaust port 65 is unmaskedand atmospheric pressure is reestablished in the cyclinder 8'2 to theleft of the piston 83 so that the latter moves to the right and throughthe linkage 88 shifts the throttle valve 90 to ordinary idling asdistinguished from fast idling position. Accordingly, the trailer engine17 is prevented from racing when the transmission 18 is shifted toneutral as would otherwise occur if it was necessary to rock the handle80 to shift the throttle valve 90 to ordinary idling position. Myirnproved arrangement therefore eliminates driver error andforgetfulness.

When the vehicle speed falls below the top regulating speed, thetransmission is immediately restored to driving range and thetransmission control vacuum valve S assumse the position shown in FIG. 5so that the vacuum pump 73 again becomes effective. Hence, since thevalve 76 is in the same position which it occupied when the trailerengine cut out, i.e., in a position wholly or partially throttling airow through the hose 71, the ensuing creation of a vacuum condition inthe cylinder 82 quickly shifts the throttle valve 90 to the positionoccupied when the trailer engine cuts out. 1n this connection, it willbe noted that when the trailer engine cuts in, its throttle valve 9i)is in ordinary idling position, but the trailer engine immediatelyspeeds up by reason of its connection to the trailer rear axle Ztl andsince the vacuum pump 73 is driven by this engine, the vacuumestablished thereby rapidly opens the throttle valve 9&1 to a positioncorresponding to the engine speed and as determined by the setting ofthe manual valve 76.

This quick opening movement of the throttle valve 95 under theconditions just stated is primarily due to the slip connection betweenthe trailer engine and transmission provided by the hydraulic couplingor torque converter as the case may be. Hence, when power flow throughthe transmission is resumed due to vehicle speed falling below the topregulating speed and communication is reestablished between the vacuumpump 73 and the cylinder 32 with the rotor 79 in at least the fastidling position shown in FIG. 6, the fact that the trailer engine ismomentarily not under load by reason of the slip connection to thetransmission enables the engine to quickly increase its speed to a pointsuiiicient to take up the load.

From the foregoing, it will be apparent that the term first automaticposition of the valve 76 means that in any position of the valve rotor'79 between the first automatic position as shown in FIG. 6 and aposition in which the rotor masks the port 77, the throttle valve 941,when the trailer engine cuts in, will be automatically returned to theposition which it occupied when the trailer engine cuts out without anynecessity for moving the handle 89,

In the case of an emergency stop, if the vehicle speed when the brakesare applied is above the top regulating speed and hence with the trailerengine idling, the trailer transmission cuts in when the speed fallssuiciently and while the throttle valve 9i? momentarily opens forreasons noted above, it quickly returns to idle position because of thedecreasing vacuum available as the speed of the engine driven vacuumpump 73 falls.

Normally, the vehicle speed represents the combined efforts of bothengines, with the trailer engine responsive thereto and not only cuttingin and out as this speed varies below and above a top regulating speed,but with the trailer power unit having the further capacity, alsoresponsive to vehicle speed, of changing speed ratios in the associatedtransmission as vehicle speed moves up and down. Even when the vehiclespeed is a function only of the tractor engine, the controls for thetrailer engine arel always tied to vehicle speed by -reason of thegovernor connection to the propeller shaft of the tractor. Further,throttle valve movements of the trailer engine, for any given positionof the handle 8%), are fully automatic between idling and whateverposition was originally determined by the handle as the trailer enginecuts in and out.

Where it is desirable to have speed ratios additional to those providedby the transmission 18, the rear axle 20 may include two speeds. In FIG.l, the trailer 12 is shown with a tandem rear axle construction andwhile either axle may be employed as the driving axle, it will beassumed that the forward axle 25 performs this function. A diagrammaticarrangement of this construction and the controls therefor are alsoillustrated in FIG. 2 which have been conveniently associated with theother mechanism in this figure already described.

Referring to FIG. 2, the fixed terminal of an axle switch 92, located inthe tractor cab, connects by a wire 93 with one terminal of the mainswitch 32. The switch 92 is selectively swingable between contacts 94and 95, the former connecting by a wire 96 with one end of the coil of alow speed solenoid 97 whose opposite end connects by a Wire 9S with thewire 33 and hence with the microswitch 26 whose closure energizes thedriving range solenoid 34. The contact connects by a wire 99 with oneend of the coil of a high speed solenoid 160 whose opposite end connectsby a wire 101 with the wire 98 and therefore with the microswitch 26.Accordingly, it will be understood that the solenoids 97 and 10G arenever simultaneously energized, but are selected depending upon the gearratio desired in the rear axle.

The solenoid 97 includes the usual core 152 which is connected at oneend by a link 103 with the free end of a rockable axle gear selector arm1t4 that is biased in the neutral or off position 105 shown by a spring106. The

solenoid 11H3 includes a core 107 whose outer end con-Y nects with oneend of a link 1118 whose opposite end carries a pin 169 that operates inan elongated slot 110 formed in the arm 104 radially inward of theconnection of the link 103 thereto. The core 192 has a longer strokethan the core 167, the former when the associated coil is energized,shifting the arm 154 to low gear position 111 while the latter, when thecoil of the solenoid 100 is energized, shifts or holds the arm to or inthe high gear position 112, the slot or lost motion connectionpermitting overriding of the pin 199 when the arm 104 is rocked toposition 111.

The rocking of the arm 104 determines the -position of an axle gearselector valve 113 which controls the admission and exhaust of air underpressure to and from a double acting piston mechanism presentlydescribed. Referring to FIG. 7 which more particularly shows the valveconstruction, it comprises a casing 114 having a cylindrical chamber 115in which rocks a similarly shaped rotor 116 to which the inner end ofthe arm 104 is connected. Aligned, radial passages 117 and 118 extendthrough the rotor 116 with their outer ends terminating at the annularsurface thereof and their inner ends communicating with a passage 119extending axially of the rotor 116. One end of the passage 119communicates through the casing 114 with la hose 120 which in turnconnects with a source of air under pressure, such as a tank 121 (seeFIG. 1) that is maintained at a predetermined pressure by conventionalmeans not shown. Air under pressure is therefore always present in thepassages 117 and 118.

Parti-annular, long and short channels 122 and 12,3 are recessed in theperipheral surface of the rotor 116, the ends of the channel 122terminating adjacent the outer ends of the passages 117 and 118, allrespectively, while the channel 123 is located on the opposite side ofthe passage 118 with one end terminating adjacent this passage and theopposite end spaced a convenient distance therefrom.

With the rotor 116 in the position shown in FIG. 7, the channel 122provides communication between passages 124 and 125 which extend throughthe casing 114 and respectively communicate with the atmosphere and withone end of a hose 126, while the channel 123 connects passages 127 and128 which also extend through the casing 114 and respectivelycommunicate with the atmosphere and one end of a hose 129.

Referring to FIG. 2, the other ends of the hoses 126 and 129respectively communicate with chambers 138 and 131 provided at oppositeends of a cylinder 132 in which is reciprocable a double acting piston133 that separates the chambers and is mounted on a rod 134 that extendsthrough one end of the cylinder and a bearing 135 spaced therefrom andforming part of a bracket 136 that is carried by the cylinder. Anabutment plate 137 is fast to the bearing 135 and a second abutmentplate 138 is positioned midway between the plate 136 and the adjacentend of the cylinder 132, both plates being coaxial with the rod 134 andthe plate 138 being secured to this rod in any approved manner. A spring139 encircles the rod 134 between the plates 137 and 138 and a similarspring 14?` is located between the plate 138 and the adjacent end of thecylinder 132. These springs are of equal strength and bias the piston133 to the intermediate position shown which determines the neutral ofthe two speed axle.

The rod 134 extends through the bearing 135 for connection with one armof a lever 141 that is pivoted on the bracket 136, the other lever armbeing connected through a link 142 with a shiftable yoke 143 havingspaced forked arms 144 and 145 which respectively engage clutch members146 and 147 splined to a jack shaft 148 which is parallel to the rearaxle 20, the arms 144 and 145 being arranged to axially shift themembers 146 and 147 while permitting rotation of the latter. One end ofthe jack shaft 148 carries a bevel gear 149 which meshes with a bevelpinion 150 secured to the output end of the propeller shaft 19. Betweenthe clutch members 146 and 147 are pinions 151 and 152 which are freelyjournaled on the jack shaft 148 and held against axial movement in anydesired manner, one side of each of the pinions 151 and 152 beingarranged for clutching engagement with the members 146 and 147,respectively. The pinions 151 and 152 mesh with gears 153 and 154,respectively, that are keyed to the rear axle 20, with the pinion 151and gear 153 constituting the low gear of the axle and the pinion 152and gear 154 forming the high gear. For

desirable to utilize the high gear of the rear axle.

10 the sake of clearness, the differential gear mechanism has beenomitted.

As noted in FIG. 2, the solenoids 97 and 100 are deenergized and thevalve 113 is in the position shown in FiG. 7 wherein the outer ends ofthe passages 117 and 118 are masked by the casing 114 and both chambers130 and 131 are at atmospheric pressure since the former communicatesthrough the-hose 126, passage 125, channel 122 and passage 124 with theatmosphere, while the chamber 131 communicates through the hose 129,passage 128, channel `123 and passage 127 with the atmosphere. Hence,the piston 133 is balanced in the neutral position shown by the springs139 and 140 and the clutch members 146 and 147 are free of engagementwith the pinions 151 and 152, respectively.

This capacity to break connection between the rear axle 211 andtransmission 18 is an important feature of the invention. 1n automatictransmissions of the Dynao and Hydramatic type, speed ratios arecontrolled by speed bands and clutches which are hydraulically actuatedby liquid discharged by pumps, one being engine driven and the otherbeing responsive to vehicle speed. Hence, when the trailer is beingtowed by the tractor, the ability to break connection between thetrailer propeller shaft 19 and trailer rear axle 20 prevents unwantedoperation of the pumps noted above and therefore possible burning out ofthe speed bands and clutches.

When the vehicle is placed in motion by the tractor engine y13, theswitch 92 is swung to engage either the contact 94 or 95. depending uponthe conditions of operation, simultaneously with or prior to the closingof the switch 30. Assuming that contact 94 is engaged, the low speedsolenoid 97 is thereby energized, thus shifting the arm 1114 to the lowspeed position 111 and rocking the valve rotor 116 counterclockwiseuntil the outer end of the passage 117 registers with the passage 125 tothereby admit compressed air through the hose 126 to the chamber 130. Atthe same time, the outer end of the passage 118 is masked by the annularwall of the chamber between the passages 127 and 128 while the channel122 provides communication between the passages 128 and 124 so that thecylinder chamber 131 is open to the atmosphere. Accordingly, the piston133 moves to the right, as viewed in FIG. 2, compresses the spring 139and through the lever 141 and link 142 shifts the yoke 143 and eectsengagement of the -low speed pinion 151. Power connection to the rearaxle 20 through the latters low speed gear is now complete and thetrailer engine can be accelerated in the manner described above.

As the speed of the vehicle rises, it will ordinarily be For thispurpose, the switch 92 is moved to engage the contact 95, thusdeenergizing the low speed solenoid 97 and energizing the high speedsolenoid 180 whereupon the arm 184 under the pull of the spring 106shifts to the high speed position 112 where it is held by the pin 109.The valve rotor 116 is thereby rocked clockwise to shift the outer endof the passage 118 from between the passages 127 and 128 where it wasmasked by the wall of the chamber 115 into registration with the passage128. At the same time, the outer end of the passage 117 moves out ofregistration with the passage and communication is established throughthe channel 122 between passages 125 and 124. Hence, compressed kair issupplied to the chamber 131 and the chamber 130 is open to theatmosphere. Accordingly, the piston 133, urged bythe hitherto compressedspring 139 and the air pressure in the chamber 131, moves to the leftand through the lever 141, link 142 and yoke 143 disengages the clutchmember 146 and engages the clutch member 147 to establish drive throughthe high gear set comprising the pinion 152. and gear 1154.

At any lspeed of the vehicle below the top regulating speed as definedabove, and while the trailer transmission l 1 18 is in low or drivingrange, either of the gear ratios in the rear axle may be selected atwill to meet road conditions, thus providing a more ilexible arrangementthan that afforded by the transmission alone.

Another important feature is the automatic shitting of the two speedrear axle to neutral when the top regulating speed of the vehicle isreached. This facility arises by reason of the tying in of the low andhigh speed circuits which control the selection of the rear axle speedswith the circuit which controls the driving range of the transmission18. At the top regulating speed, the microswitch 26 opens which not onlydeenergizes the driving range solenoid 34 so that the transmission gearselector arm 46 returns to neutral position 52, the low range solenoid28 having previously been deenergized, all as described above, but alsoeither the low speed solenoid 97 or the high speed solenoid 100 isdeenergized depending upon the position of the axle switch 92 so thatthe rear axle structure is conditioned for neutral. Further, when thespeed of the vehicle falls below the top regulating speed, the closingof the microswitch 26 simultaneously energizes the solenoid 34 andeither the solenoid 97 or the solenoid 100 to thereby restore thetransmission '18 and rear axle 20 to power transmitting condition. Inother Words, the transmission and the rear axle gear sets aresimultaneously and automatically conditioned for power transmissionbelow a determined vehicle speed and simultaneously and automaticallyshifted to neutral above this speed without any requirements on the partof the driver.

Where the complete system as shown in FIG. 2 is employed, the switch 3,2serves as a single cut-out switch whose opening interrupts all circuitsand therefore provides a convenient device for quickly shifting thetransmission and rear axle to neutral in the event of an emergency stopof the vehicle.

Referring to FIG. 8, there is schematically shown a modified vacuumcontrol system for the booster engine throttle valve whose automaticconditioning is determined by positions of lthe primary engine throttleand therefore related to the speed of the latter engine, or, in otherwords, the vacuum system is responsive to the speed of the propellingconnection to the axle means. In FIG. 2, the automatic positioning ofthe throttle of the trailer engine 17, is governor responsive to thespeed of the propelling connection to the axle means, Hence, in allvariations disclosed herein, automatic positioning of the trailer orbooster engine throttles is responsive to vehicle speed.

Since some ot the parts in lthe FIG. 8 vacuum system are generallyidentical in structure and function with the corresponding system partsshown in FIG. 3, they are identified by like numerals.

The vacuum pump 73 connects by pipe 194 with one branch of a T 195 and apipe 196 connects a second branch of this T with the vacuum cylinder 82on the spring loaded side of the piston 83. The third branch of the T195 connects by pipe 197 with a port 198 pro vided in a casing 199forming part of a vacuum valve 200 whose operation is controlled by theaccelerator pedal for the primary engine as presently described.Rockable within the casing 199 is a rotor 201 which includes on theperipheral surface thereof a parti-annular channel 202. Generallyopposite to the port 198 and in the casing 199 is a second port 203 thatconnects through pipe 204 with the passage 74 in the vacuum valve 76 andhence with the port 77 thereof. The casing 199 also includes a thirdport 205 which communicates with the atmosphere at one end and .at theopposite end with the channel 202 during a determined movement of therotor 201 as presently explained.

Secured to the roto-r 201 externally of the casing 199 is a lever 206,one arm of which connects through appropriate linkage 207 with theaccelerator pedal 208 for the primary engine While the other arm 209connects with the throttle (not shown) of the primary engine. With therotor 201 in the position shown in FIG. 8, the primary engine is ildingand the atmosphere port 205 is uncovered and connects through thechannel 202 with the ponts 19S and 203, For convenience, the manualvacuum valve 76 is shown in the first automatic position as definedabove and as shown in FIG. 6 for the FlG. 2 control.

By way of example, the operation of the vacuum control system shown inFIG. 8 will be described in connection with the vehicle shown in FIG.11. rl`his control is concerned only with an automatic response of thethrottle of the booster engine 178 to the speed of its propellingconnection and not with an additional and linked control of thetransmission as shown in FIG. 2. The lat-ter may consist of `any of theautomatic types of transmission referred to above which obey their ownlav/s as to shifting, or it may be a selectively controlled, clash geartype. The latter will be considered as included in the FIG. ll vehicle.

Considering the FIG. 1l vehicle at rest with both engines idling andassuming equal size engines, the clutch 182 disengaged, and thetransmission 183 in some selected gear, it will be apparent that theidling speeds of both engines will be identical since they connect tothe common transfer case 181. The rotor 201 is in the position shown inFIG. 8 which determines the idling position of the throttle of theprimary engine 177 and while the manual vacuum valve 76 is in the firstautomatic position, the uncovering of the port 205 by the rotor 201prevents the vacuum pump 73 from establishing any vacnum in the cylinder82 so that the throttle of the booster engine 178 is in ordinary idlingposition. In other words, the capacity of the vacuum pump 73 at the thenspeed of .the booster engine 178 in relation to the then sizes of theports 77 and 205 is such that all of the air intake to the pump 73 isthrough the ports 77 and 205 and no air is drawn from the vacuumcylinder 82 so that the piston 83 is in the ordinary idling positionshown in FIG. 8.

It will be apparent therefore that any reduction in the size of eitherthe port 77, or the port 205, or in both of them, provides a control onthe creation of a vacuum in the cylinder 82 and hence on the position ofthe throttle of the booster engine 178.

The accelerator pedal 208 is then depressed to rock the rotor 201counterclockwise and further open the throttle of the primary engine177, the clutch 182 is engaged and the vehicle begins moving. Since thebooster engine 178 is tied in with the rear axle 184, the revolutionsper minute of this engine always bear a direct ratio to the speed ofthis axle. Hence, as the vehicle accelerates, the speed of the boosterengine 178 also increases along with that of the vacuum pump 73 driventhereby yand since the movement of the rotor 201 is in a directiontowards gradual closing of the port 205, air movement through this portbecomes more restricted. Therefore, at this increased speed of theVbooster engine v178, the vacuum pump 73, having its total intake throughthe ports 205 and 77 (first automatic position) decreased, beginswithdrawing air from the vacuum cylinder 82 and atmospheric pressureshifts the piston 83 towards the left in FIG. 8 to effect an openingmovement of the throttle of the booster engine 178 whose extent willdepend upon the speed of the booster engine.

In all positions of the rotor 201 between full opening and full closingof the port 205, not only will the throttle position of the primaryengine 177 and hence its speed vary, but for any given position of themanual control valve 76, the throttle position of the booster engine 178will also vary and this latter variation will be automatic and in directratio to the speed of the axle 184. When the port 205 is fully closed bythe rotor 201, control on the booster throttle is shifted to the port77.

Automatic positions of the manual vacuum valve 76 range from the firstposition generally shown in FIG. 8 to a full closure of the port 77, itbeing understood that the valve 76 is manually placed in any of thesepositions, the term automatic referring to the booster engine throttleresponse. When the port 77 is closed, vacuum control shifts to the port205. Within the automatic range and short of full closure of the port77, the booster engine supplies a minimum of about and about a maximumof 30% of its power. An increase in booster engine power above thismaximum can be obtained by manually actuating the valve 76 to fullyclose the port 77 and `assuming a full closure of the port 205.

Further, the control shown in FIG. 8 may also be applied to the trailerengine 17 in FIG. 1 which also connects with a vehicle axle and asschematically shown in FIG. l2. Functionally, the valve 2011 hasattributes similar to the valve 58 in FIG. 2.

FIG. 12 schematically shows the application of the FIG. 8 control to atractor-trailer vehicle and, by way of example, the numericaldesignations are respectively identical with those applied to theengines and transmissions of the tractor and trailer in FIG. l, and withthose applied to the primary or tractor engine throttle and booster ortrailer engine throttle controls in FIG. 8. Accordingly, the trailertransmission 18 may be any ofthe automatic types referred to above whichare conditioned for drive therethrough in the Well known manner, such asby suitable linkage controlled from the cab of the vehicle. However,since the FIG. 8 control is concerned only wit-h determining positionsof the booster engine throttle, the booster engine transmission ismerely incidental and only forms a part of the propelling connection tothe associated rear axle. Hence, so far as the application of the FIG. 8control is concerned, the type of booster engine transmission is notimportant and it may be any of the well known non-automatic types ofgear transmissions whose drive settings are remotely controlled from thecab, either pneumatically, hydraulically or electrically as disclosed,for example, in U.S. Letters Patent No. 2,140,109, dated December 13,1938. Accordingly, the transmission 18 in FIG. 12 is deemed to berepresentative or" automatic and non-automatic transmissions and, forany type thereof, power flow is through the propeller shaft 19 to theusual rear axle 236.

In FIG. 9 is schematically and sectionally shown a modified valve 211)which may be substituted for the valve 211i? in the FIG. 8 control andwhose operation eliminates any necessity for closing the port 77 by amanual shift of the valve 76 when full power is desired from the boosterengine 178 in FIG. 11 or the trailer engine 17, assuming that the valve211i is associated therewith. Certain parts are functionally identicalwith some shown in FIG. 8 and are denoted by the same numerals.

Specifically, the valve 21) includes a casing 211 having a chamber 212extending longitudinally thereof and reciprocable in this chamber at oneend thereof is a piston valve 213 carrying a prong 213a which connectswith the accelerator pedal 2113 in such a way that a depression of thepedal shifts the valve 213 towards the left. A second piston valve 214is shiftably positioned in the chamber 212 in spaced relation to thepiston valve 213. A helical spring 215 is interposed between the opposedends of the valves 213 and 214 and another helical spring 216 isinterposed between the other end of the valve 214 and a disk 217 whichcloses the end of the chamber 212 remote from the valve 213. The spring215 is characterized by a substantially lower rate than the spring 216for a purpose presently explained.

A transverse passage 21S extends inwardly from the periphery of thecasing 211 where it communicates with the atmosphere to intersectionwith the chamber 212 and to form a port 219 whose function is similar tothe port 2115 in FiG. 8, as presently explained. A short, transversepassage 221) is positioned in opposed relation to the port 219 andprovides communication `between the opposed ends of the piston valves213 and 214 from the chamber 212 to a longitudinal passage 221 that iswholly included in the casing 211. A short, transverse passage 222connects the passage 221 with the portion ofthe chamber 212 to the leftof the piston valve 214 and also communicating with the same chamberportion is the pipe 2114 leading to the manual vacuum valve 76. Further,the pipe 194 leads from the passage 221 to the vacuum pump 73 and alsoconnects with the pipe 196 leading to the vacuum cylinder 82.

The valve 210 is shown in the same functional position as the valve 2150in FIG. 8, i.e., both engines idling, the piston valve 213 fullyuncovering the port 219 corresponding to the like position of the rotor201 relative to the port 205, and the piston valve 214 fully uncoveringthe passage 222. For normal operation short of full opening of thetrailer engine throttle, the valve 210 is functionally equivalent to thevalve 200 in that depressions of the `accelerator pedal 208 shift thepiston valve 213 towards the left to vary the opening of the port 219and hence, for any given setting of the valve 76, exerting a control onthe throttle of the trailer engine 17 in the manner described above.These movements of the piston valve 213 `do not alect the piston valve214 because of the softer nature of the spring 215.

For full trailer engine throttle, the accelerator pedal 2118 is fullydepressed and the piston valve 213 is shifted suiciently to move thepiston valve 214 to close the passage 222, thus denying air ow throughthe port 77 in any automatic position of the valve 76 and enabling thepiston 83 to shift the throttle of the trailer engine 17 to full openposition.

Where the valve shown in FIG. 9 is used in a tractortrailer vehicle asgenerally shown in FIG. 1, it is desira'ble to make provision for theIsituation where the driver, in moving the vehicle in reverse, employsonly the primary engine arid does not wish to change any forward speedrelation that exists in the transmission connection to the trailerengine. This is accomplished by the auxiliary control schematicallyshown in FIG. 10 which prevents opening of the trailer engine throttlewhen the accelerator pedal for the primary engine is depressed.

Referring to FIG. 10, the numeral 223 designates a safety valveincluding a casing 224 and a rotor 225 rockable therein provided with aparti-annular channel 226 around its peripheral surface. Spaced ports227 and 228 extend through the wall of the casing 224, the port 227connecting through a pipe 229 with the pipe 196 leading to the vacuumcylinder 82 and the port 228 providing communication between theatmosphere and the channel 226.

Externally of the casing 224, the rotor 225 is fast to one end of a rockarm 230 whose opposite end connects with a core 231 operably related toa solenoid coil 232 that is included in an electric circuit having abattery 23g and a switch 234 conveniently located in the vehicle caDuring all forward operations, the switch 234 is open and the rotor 225is in the position shown wherein it masks the port 227, but beforeexecuting a reverse movement of the vehicle in the manner referred toabove, the switch 234 is closed to thereby energize the coil 232 andeffect a clockwise rocking of the rotor 225 to connect the ports 228 and227 through the channel 226. Hence, regardless of the extent of openingof the primary engine throttle, the throttle of the trailer engine willremain unaffected since the vacuum pump will merely pull air through theport 228 and no vacuum will be established in the vacuum cylinder 82.

I claim:

1. In 'a motor propelled carrier, the combination of an engine having athrottle valve therefor and drivably connected to an axle of the carrierand a remotely controlled vacuum system for determining positions of thethrottle valve comprising a vacuum pump driven by the engine, a cylinderhaving a piston reciprocable therein and connected to the throttlevalve, the piston being constantly subjected to atmospheric pressure onone side and biased on the other side to a position determining theidling position of the throttle valve, first valve means having anexhaust port and shiftable between a position closing the exhaust portand establishing a vacuum creating connection of the pump with thebiased side of the piston and a position breaking said connection andconnecting the biased side of the piston to the exhaust port, andmanually controlled valve means having a constantly open vent port and apassage communicating with the first valve means and operable toregulate air ow from the vent port through the passage when the pump isconnected to the cylinder to vary the extent of vacuum therein and theposition of the throttle valve.

2. In a motor vehicle, the combination of a primary engine, a boosterengine, each engine having a throttle and propelling connections to axlemeans of the vehicle, lever means for controlling the position of theprimary engine throttle, Vand a vacuum system for determining positionsof the booster engine throttle comprising a positive displacement vacuumpump driven by the booster engine, a` cylinder having a pistonreciprocable therein and connected to the booster engine throttle, thepiston being constantly subjected to atmospheric pressure on one sideand biased on the other side to a position determining the idlingposition of the booster engine throttle, means connecting the vacuumpump to the cylinder on the biased side of the piston, valve meansresponsive to the lever means having an atmosphere connecting port andpassage means connecting with the vacuum pump and the biased side of thepiston and shiftable between a position placing the atmosphere port incommunication with the biased side of the piston and a position closingthe atmosphere port, and manually controlled valve means having aconstantly open Vent port and a passage communicating with the leverresponsive valve means and operable to regulate air ow from the ventport through the lever responsive valve means to vary the extent ofvacuum in the cylinder.

3. In a motor Vehicle, the combination of a primary engine, a boosterengine, each engine having a throttle and propelling connections to axlemeans of the vehicle, pedal means for moving the primary engine throttlebetween idling and full open positions, and a vacuum sys tem fordetermining positions of the booster engine throttle comprising apositive displacement vacuum pump driven by the booster engine, acylinder having a piston reciprocable therein and connected to thebooster engine throttle, the piston being constantly subjected toatmospheric pressure on one side and biased on the other side to aposition determining the idling position of the booster engine throttle,means connecting the vacuum pump to the cylinder on the biased side ofthe piston, valve means responsive to the pedal means having anatmospheric connecting port and passage means connecting with the Vacuumpump and the biased side of the piston and shiftable between a positionplacing the atmosphere port in communication with the biased side of thepiston to determine the idling position of the booster engine throttleland a position closing the atmosphere port, manually controlled valvemeans having a constantly open vent port and a passage communicatingwith the pedal responsive valve means and operable to regulate air iiowfrom the vent port through the pedal responsive valve means to vary theextent of vacuum in the cylinder, and means forming a part of the pedalresponsive valve means for interrupting communication between the vacuumpump and the manually controlled valve means when the primary enginethrottle is fully opened.

4. In a motor propelled carrier, the combination of an engine having athrottle valve therefor and drivably connected to an axle of the carrierand a remotely controlled nected to the throttle valve, the piston beingconstantly subjected to atmospheric pressure on one side and biased onthe other side to a position determining the idling position of thethrottle valve, first valve means having an atmosphere connecting port,piping means connecting the vacuum pump and the biased side of thepiston with the first valve means, the first Valve means being shiftablebetween a position placing the fully open atmosphere port incommunication with the biased side of the piston and any positionincluding part and full closure of the atmospliere port in which thevacuum pump develops a condition of vacuum on the biased side of thepiston, and manually controlled valve means having a constantly openvent port and a passage communicating with the first valve means andoperable to regulate air flow from the vent port to vary the extent ofvacuum in the cylinder.

5. A motor propelled carrier as defined in claim 4 wherein the firstvalve means includes a casing provided with the atmosphere connectingport and other ports respectively connecting with the piping means andpassage, and a rotor in the casing including a parti-annular channelrecessed therein and constituting a duct means, the rotor being rockablebetween positions opening and closing the atmosphere port.

6. In a motor vehicle, the combination of a primary engine, a boosterengine, each engine having a throttle and propelling connections ytoaxle means of the vehicle, lever means for controlling the position ofthe primary engine throttle, and a vacuum system for determiningpositions of the booster engine throttle comprising a vacuum pump drivenby the booster engine, a cylinder having a piston reciprocable thereinand connected to the booster engine throttle, the piston beingconstantly sub1 the other side to a position determining the idlingposi- -tion of the booster engine throttle, valve means responsive tothe lever means and having an atmospheric connecting port, piping meansconnecting the vacuum pump and the biased side of the piston with thevalve means, the valve means being shiftable between a position placingrthe fully open atmosphere port in communication with the biased side ofthe piston and any position including part and full closure of theatmosphere port in which the vacuum pump develops a condition of vacuumon the biased side of the piston, and manually controlled valve meanshaving a constantly open vent port and a passage communicating with thelever responsive valve means and operable to regulate air flow `from thevent port to vary the extent of vacuum in the cylinder.

7. A motor vehicle as defined in claim 6 wherein means forming a part ofthe lever responsive valve means is provided for interruptingcommunication between the vacuum pump and the manually controlled Valvemeans when the primary engine throttle is fully opened.

References Cited in the file of this patent UNITED STATES PATENTS1,768,530 Short .Tune 24, 1930 1,868,130 Baurer et al. July 19, 19322,948,926 Dillon July 28, 1936 2,140,109 Kellar Dec. 13, 1938 2,235,175Simpkins et al Mar. 18, 1941 2,343,265 Price Mar. 7, 1944 2,384,782Rockwell et al Sept. 11, 1945 2,419,807 Wilcox Apr. 29, 1947 2,419,811Beall Apr. 29, 1947 2,419,912 Ormsby Apr. 29, 1947

